Sheet metal contact



Nov. 22, 1960 H. A. ELLIOTT ETAL SHEET METAL CONTACT Filed June 9, 1958 III-i=4 Z4 INVENTORS HowA/w A ELL/arr WILLIAM M PHAIL United States Patent SHEET lVIETAL CONTACT Howard A. Elliott and William McPhail, Detroit, Mich., assignors to Essex Wire Corporation Filed June 9, 1958, Ser. No. 740,876

4 Claims. (Cl. 339-276) This invention relates to sheet metal electrical contacts for electrical connectors and more particularly to improvements in the construction of electrical contacts particularly Well suited for use in small electric sockets such as are employed to receive low voltage electrical bulbs.

There has now come into relatively wide-spread use a type of contact for such lamp sockets comprising a sheet metal member having a cup-shaped hollow head integrally connected by a neck portion to a wire-receiving portion having U-s haped lugs. An example of such a contact is disclosed in Patent No. 2,142,818, granted January 3, 1939 to G. W. Jacobson.

Although contacts of this type are particularly suited for economical manufacture and attachment to conductors by mass production methods, difficulty has been experienccd with their use. The thin metal neck connecting the contact portion to the wire-receiving portion does not have suflicient strength to withstand the bending forces frequently applied to it in handling and installation of the lamp socket in which the contact is employed. Good electrical connections cannot be made between the lamp and such bent contacts, and it is necessary to rep-lace the lamp socket after it has been completely installed. In certain applications, the replacing operation may be considerably more costly than the mere cost of the defective lamp socket.

It is an object of this invention to provide a contact of the foregoing character wherein the contact pontion has an improved mechanical connection with the wire-receiving portion, which contact may be simply and inexpensively fabricated as a unitary stamping.

The present invention provides a contact that has sufficient strength to withstand the bending forces encountered in handling and installation with only an inconsequential increase in cost. In a preferred embodiment, this is accomplished by providing the contact portion with an integral tongue or extension which extends in the same direction as the connecting neck portion to be secured in position by conductor securing lugs to provide second means for fastening the contact portion to the wiresecuring portion of the contact.

The principles and details of construction of this particular embodiment and other objects and advantages will be apparent from the following description considered in connection with the accompanying drawings in which:

Figure l is a side view partially in section showing a contact made according to this invention utilized in a lamp socket, showing a lamp bulb in position and a conductor.

Figure 2 is an enlarged plan view of the contact fastened to a conductor prior to its assembly in the lamp socket.

Figure 3 is a plan view of the contact shown in Figure 2 before assembly on the conductor.

Figure 4 is a side view of the contact shown in Figure 3.-

Figure 5 is an end view of the contact shown in Figure 3 as taken from the right side of Figure 3.

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Figure 6 is an end view of the contact shown in Figure 3 as taken from the left side of Figure 3.

Figure 7 is a sectional view taken on the line 7--7 of Figure 6.

Figure 8 is a plan view of the strip from which the contact of Figure 3 is obtained.

Referring now to the drawing, the improved contact of this invention is preferably formed from a blank of sheet metal which may be of the shape illustrated in Fig ure 8. At one end of the blank a cable securing portion 10 is slotted to provide a pair of insulation grip-ping lugs 12 and a pair of conductor gripping lugs 14. The lugs 12 and 14 are bent or curved to the position shown in Figures 3, 4, and 6 for reception of the terminal end of the cable.

Extending centrally from one end of the cable securing portion 10 is a neck portion 16 which is integrally connected to a contact portion 18 of generally circular outline. Contact portion 18 is dished to provide a contact member of generally semicyl-ind-rical or semi-hemispherical shape. The neck portion 16 is bent to position contact portion 18 substantially perpendicular to the longitudinal axis of the cable securing portion '10, the contact portion being preferably offset downward slightly from the cable securing portion 10 as seen in Figures and 7.

Extending from the contact portion 18 di-arnterically opposite neck portion 16 is an' extension or auxiliary neck portion 20 of relatively longer length than the neck portion 16. The extension 20 is bent intermediate the opposite ends thereof as at 22 dividing extension 20 into end parts 24 and 26. Extension 20 is also bent adjacent its junction with contact portion 18 in such manner that end part 26 of extension 20 lies in parallel relation with the cable securing portion 10 intermediate lugs 14. As shown inFigures 3, 7, and 8, end part 26 is provided near its freeend with a transverse embossed portion 28 projecting away from portion 10. I

In attaching the contact to a cable 30, the terminal end of cable 30 is inserted between lugs 12 and 14 with the bared conductor 32 of the cable lying upon the end part 26 of extension 20. The upstanding end part 24 serves as a stop to correctly position the end of the bared conductor 32. The ends of the lugs 12 are then bent about the sheath 34 of the cable 30 while the lugs 14 are bent around and crimped upon the bared conductor 32 simultaneously clamping the end part 26 of extension 20 in position. Embossed portion 28 serves as a mechanical key against pull-out of both the conductor 32 and the extension 20. It can be readily seen that the contact portion 18 is attached to the cable securing portion 10 of the contact at two diametrically opposite sides.

Referring now to Figure 1 of the drawing there is shown a lamp socket 36 formed of insulating material having a passage 38 in which the cylindrical base 40 of a lamp bulb 42 is positioned. As shown, the contact of the invention is mounted in a reduced diameter portion 44 of passage 38 with the contact portion 18 of the contact engaged by a contact 46 of conventional type carried on the end of the lamp bulb base 40. Cable 30 secured to the contact extends through a small opening 48 at the end wall 50 of passage portion 44. Positioned in the passage portion 44 and surroundingcable securing portion 10 of the contact and the adjacent portion of cable 30 is a coil spring 52 one end of which engages the end wall 50 of socket 36 while the other end engages neck portion 16 and extension end part 24 of the contact adjacent their junction to contact portion 18.

From the foregoing, it will be apparent that the contact embodying the invention is well-adapted for the attainment of the object set forth above, the construction requiring a minimum of additional material and forming operations. It will also be apparent that the contact embodying the invention can be manufactured and attached to a cable economically by means of conventional app-a- -r-atus and techniques.

Although the contact of the invention has been shown as adapted to a lamp socket, it will be understood by those familiar with this art that the same general construction of this contact may be adapted for use in other types of sockets and connectors. While the invention has been illustrated and described in its preferred embodiment and has included certain details, it should be understood that the invention is not to be limited to the precise details herein illustrated and described since the same may be carried out in other ways falling within the scope of the invention as claimed.

What is claimed is:

1. An electrical contact formed from a sheet metal blank, the blank having a generally circular contact portion, a neck portion and a relatively longer extension portion disposed upon diametrically opposite sides of the contact portion, and a conductor securing portion attached to the neck portion and including a pair of clamping lugs; said contact portion being dished to facilitate its engagemeat with another contact element; the neck portion being bent to position the contact portion at substantial-1y a right angle to the longitudinal axis of the conductor securing portion; the extension portion being bent intermediate its ends to provide a first part adjacent the con- 7 tact portion and a second part remote from the contact portion; said first part being bent adjacent its junction to the contact portion to permit the second part to overlie the conductor securing portion intermediate the lugs; said extension portion stiffening the contact portion against bending when the conductor securing portion is crimped about the second part of the extension portion.

2. The contact of claim 1 wherein the second part of the extension portion is provided with a transverse embossed portion.

3. In a one-piece sheet metal electrical contact comprising a dished contact portion, an integral shank portion extending from one edge of the contact portion, lugs extending from the shank portion for folding upon said shank portion, and said shank portion being bent to extend in the same general direction as the concave surface of the contact portion faces; the improvement in said contact wherein the contact includes an integral extension portion extending from another edge of said contact portion opposite said first edge, said extension portion being bent to provide a first portion angularly inclined with respect to said shank portion to overlie the concave surface of said contact portion, the first portion of said extension portion terminating in an end portion extending in the same general direction as said shank portion and in superimposed relation thereto, and said end portion being positioned adjacent said lugs to be securely held in place when said lugs are folded upon said end portion for resisting displacement of said contact portion relative to said shank portion.

4. The contact according to claim 3 wherein said lugs and shank portion are formed prior to folding of said lugs upon said extension end portion to define a longitudinally extending channel in which said extension end portion is seated, said extension end portion having a transverse embossed portion defining a raised portion extending crosswise in said channel, an electrical conductor having its end seated in said channel upon said extension end portion, and said lugs being crimped over and engaging said end of said conductor so as to simultaneously clamp said conductor end and said extension end portion between said shank portion and said lugs.

References Cited in the file of this patent UNITED STATES PATENTS 1,067,702 Wiegand July 15, 1913 1,309,887 Fulton July 15, 1919 2,142,818 Jacobson Jan. 3, 1939 2,501,007 Sanger-Stevens et al 2. Mar. 21, 1950 2,718,627 Swenson Sept. 20, 1955 2,747,171 Martines May 22, 1956 FOREIGN PATENTS 639,651 France June 27, 1928 

